Judgment and decision-making biases as a function of task: Conjunction effects in explanations, inferences, and predictions
John Leddo, Ivy Liang, Smaran Pasupulati, Riya Pasupulati
An enormous amount of research has been conducted that documents judgment and decision-making biases when dealing with situations involving uncertainty. The results of these experiments are generally taken as evidence that people have weaknesses when they reason about situations requiring the application of probabilistic or statistical concepts. One such paper documented that when asked to explain why events occurred, people rated a conjunction of two explanations as being more likely to have influenced the outcome than the explanations’ individual components, a statistical impossibility given that a conjunction of two events cannot be more likely than their individual component events (Leddo, Abelson and Gross, 1984). The present research explores the hypothesis that the nature of the task that people are asked to perform may also contribute to the biases observed in these experiments. Here, high school participants were asked to rate the probability of both individual and conjoint explanations as in Leddo et al. (1984). However, other participants were given the same scenarios and asked to state the probability that individual or conjoint events were either true (inference) or likely to happen (prediction). Results confirmed the hypothesis that conjunction effects (rating two events as more probable than one) were strongest in explanations and weakest in predictions. This suggests that the task a person is asked to perform may contribute to whether or not people show biases in judgment and decision making.